Southern California Expands Water Purification

By Elizabeth Freed

Mar 08, 2012

The Orange County Water District (OCWD) Board of Directors recently approved a plan to expand the Groundwater Replenishment System (GWRS) estimated for completion by September 2014. The facility currently produces 70 million gallons per day of potable water; the expansion would add to the capacity by 30 million gallons per day. The California Department of Water Resources awarded the OCWD $1 million in grant money to contribute to the $156.2 million project. Groundbreaking for the expansion occurred on January 17, 2012.

“The GWRS established the benchmark for international water projects and water reuse technology,” OCWD General Manager Mike Markus said at the event. “Most importantly, the GWRS has provided a reliable, locally-controlled source of water for Orange County during a time when the availability of imported water is decreasing while its cost is increasing…The GWRS Expansion will provide us with the water supply reliability that we need while creating hundreds of local jobs that will benefit Orange County’s economy through the development, construction and operation of the project.”

The GWRS treats wastewater through three processes: microfiltration, reverse osmosis and ultraviolet light with hydrogen peroxide. The purified water is then split with about half (35 million gpd) pumped into injection wells where it serves as a seawater intrusion barrier, which constantly threatens groundwater basins. The other half is diverted to a 10-mile-long pipe to recharge basins in Anaheim, California. This water firters through sand and gravel to replenish the deep aquifers of Orange County’s groundwater basin and ultimately becomes part of the drinking water supply.

The expansion would add to the existing microfiltration facility by constructing eight new below-ground treatment basins and enlarging the existing basement facility. Other work includes construction of a new 32,000-square-foot reverse osmosis building, the installation of five new ultraviolet light treatment trains to match the existing systems as well as retrofitting the existing post-treatment systems to employ a new lime feed system. The project will also construct two above-ground steel tanks, with capacities to hold 7.5 million gallons of water each.

The GWRS is the largest advanced water treatment facility of its kind in the world and has garnered more than 35 regional, state and international awards. The expansions will produce water at one-half the energy currently required to import water into Orange County and one-third the energy to desalinate seawater. It also helps decrease the amount of wastewater discharged in the Pacific Ocean. When completed, GWRS will produce enough water to serve 850,000 people.